Debarking machine



Aug. 4, 1931. H. s. MITCHELL ET AL DEBARKING MACHINE Filed May 22, 1929 Patented Aug. 4, 1931 HENRY S. MTCI-IELL, OF PORTLAND, OREGCN, AND RALPH V. SCI-IAFER, OF VAN- COVEPU, W'AHINGTON DEBARKING MACHNE Application filed May 22,

Our invention relates to machines for removing the bark from relatively light pieces of lumber such as bark slabs and the like.

The object of our invention is. to provide i 45 a simple and practical machine for removing the bark from relatively light pieces of lumber such as the rounded outer surfaces of the so-called bark slabs which are sawed from the log in the mill, or the unsawed logs of '1'0 relatively small diameter, in order to render the said wood suitable to be used in the manufacture of paper pulp and the like, which is otherwise too small and light to be of any practical value in this respect.

A further object of our invention is to provide a debarking machine, provided with a longitudinally concaved cutter head, carrying correspondingly concaved knives, whereby the cutting edge of the knives will con- 20 form more or less to the rounded outer surfaces of the wood being debarked so that the knives will be supported along their entire length by the cutter head in order to withstand the severe duty imposed on them when 25 they strike the solid wood port-ions and knots ofthe slabs or small logs being operated upon.

A still further object of our invention is to provide a debarking machine of this 36 character adapted by simple means to be adjusted to the thickness of the bark being removed so that the underlying wood will not be touched by the knives of the machine H V and hence not removed with the bark.

35' A further object of our invention is to provide amachine sov simple in operation that the slab or timber to be debarked may be placed on the machine and guided during M the debarking operation by one man.

-We attain these objects in a debarking machine comprising a frame, a work supporting table on said frame, comprising` an elongated casting having sloping sides receding upward to a narrow work-supporting top, one

' side of the said table being hinged to the said frame, the longitudinal middle of the table provided with a concave depression in which to seat the work, and such depression pro- I, vided with an opening, a longitudinally conm caved cutter head rotatably supported in 1929. Serial No. 385,987'.

ln the drawings: w Fig. l shows a front elevation of our debarking machine partlf' in section and illustrates a wood slab in position on the machine to be operated upon;

F ig. 2 shows a top plan view of our machine with one of the hed plates removed;

F ig. 3 shows a perspective view of tac bed plate removed from the machine;

Fig. d shows a section taken on the line d d of Fig. 2 75 Fig. 5 shows a similar enlarged section to that of Fig. d and illustrates a wood slab being operated upon by the machine;

Fig. 6 shows a central longitudinal section of the cutter head removed from the machine and without the knives or knife holding means;

F 7 shows a front elevation of one of the knives removed from the cutter-head; and

Fig. 8 shows similarly the knife holding bar removed from the cutter-head.

Vith reference to the figures our machine comprises a support-ing frame a shown in this embodiment of our invention with two similar bark removing elements which are identical and only one of which will be described; similar reference characters indicate similar parts ofthe other debarking element.

A cutter-head 7) is carried on a horizontal shaft c journaled in the frame a as at (l and g5' driven by an electric` motor c, or other suitable driving means. 'l` he cutter head is concave, see Figures l and 6, and is provided with longitudinally concaved knives g, see Fig. 7, mounted in knife receiving slots z, and held therein by bearing bars i, see Figs. 5 and 8, and set screws j.

A work supporting table 73 is provided, adapted to be hingedly mounted on the frame a over the cutter head o, on lugs c, as at 762, and to be adjustable relative to the cutterhead by means oit al set screw 7c which bears on an oppositely arranged ledge a of the trame so that by adjusting the set screw k3 the heights of the table are varied relatively to the knives g so that t ie depth to whichthey will operate on the work may be adjusted.

The work table is provided with a central transverse concave portion p in which is formed an aperture Z through which the cutter head projects. The work table 7c is also beveled on its edges as at m to permit a wood slab or the like to be moved longitudinally thereon with a minimum of resistance.

In the operation of our machine a wood slab indicated by a: is moved longitudinally over the concave portion of the work table by an attendant so that the. knives ot' the cutterhead may operate upon the bark toV remove it. In order that all portions of th" slab will be operated upon, the attendant rocks the slab sideways in order'to bring every portion of it into contact with the cutter head, see Fig. 5, and the beveled or sloping sides m permit theoperator to bring his hands into close proximity with the cutter head, thereby to facilitate the manipulation of the slab in bringing every portion into contact with the cutter head.

Thus, by this construction we have provided a slab debarking machine which is simle of construction and operation and by which the bark covering of wood slabs or logs of relatively small diameter may be rapidly and economically operated upon.

Also, by providing a concave cutter head for holding and supporting` the concaved knives, the knives are supported along their entire length and thus strengthened in order to withstand the heavy duty to which they are subjected. I Y

Further, the strain 'on the cutter-head is so severe that ordinary cast iron or cast steel has not the required toughness and we have found it preferable to use mild steel of a similar metal more adapted to withstand the shock of the impact of the knives on the work.

l/Ve have shown only one means Jfor relatively adjusting the depth of cut of the knives of the cutter-head, believing that the means so vprovided are most practical from a mechanical standpoint, with regard to simplicity, convenience, etliciency and economy in construction. But it is self-evident that if simplicity is not to cut any ligure in the construction ot our debarking machine the parts by which the said variation in depth of cut of the cutter-head is edected, could be readily rearranged so that instead of making the table adjustable towards and Jfrom a stationary axis of rotation of the cutter-head, the table could be made stationary, and said axis of rotation adjustable and in that way accomplish the same end.

Ve claim:

1. ln a debarking machine ofthe character described, in combination with-a rotary cutter head, of a work supporting table extending parallel with the axis .of the cutter head, said table provided with a central transverse work supporting depression, said depression having an opening through which the cutter head projects, t ie side walls of said depression narrowing upwardly to reduce the area-of contact between the work supporting depression andthe work, the top of the supporting table extending laterally on both sides of but receding from said depression into a narrow ledge the depending sides of which are sloped, whereby to permit the hands or the operator to be brought into close proximity with the cutter head while manipulating the work.

2. ln a debarlring machine of the character described, in combination with a standard and rotary cutter head, of a work supporting table hinged on one side to said standard and extending parallel with the axis of the cutter head, said table provided with a central transverse work supporting depression, said depression having an opening through which the cutter head projects, a set screw threaded through the other side of said table and bearing on said standard for adjusting the top relatively to the cutter head, the side walls of said depression narrowing upwardly to reduce the area of contact between the work supporting depression and the work, the top oi:V the supporting table extending laterally on both sides of but receding from said depressioninto a narrow ledge the depending sides ot which are sloped, whereby topermit the hands of the operator to be brought int-o close proximity with the cutter head while manipulating the work. i

HENRY S. MITCHELL. RALPH V. SCHAFER.

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